bcache: Convert try_wait to wait_queue_head_t

We never waited on c->try_wait asynchronously, so just use the standard
primitives.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>

drivers/md/bcache/bcache.h

@@ -735,8 +735,8 @@ struct cache_set {
 	 * basically a lock for this that we can wait on asynchronously. The
 	 * btree_root() macro releases the lock when it returns.
 	 */
-	struct closure		*try_harder;
-	struct closure_waitlist	try_wait;
+	struct task_struct	*try_harder;
+	wait_queue_head_t	try_wait;
 	uint64_t		try_harder_start;
 
 	/*

drivers/md/bcache/btree.h

@@ -326,7 +326,7 @@ static inline void rw_unlock(bool w, struct btree *b)
 ({									\
 	int _r, l = (b)->level - 1;					\
 	bool _w = l <= (op)->lock;					\
-	struct btree *_child = bch_btree_node_get((b)->c, key, l, op);	\
+	struct btree *_child = bch_btree_node_get((b)->c, key, l, _w);	\
 	if (!IS_ERR(_child)) {						\
 		_child->parent = (b);					\
 		_r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__);	\
@@ -356,6 +356,11 @@ static inline void rw_unlock(bool w, struct btree *b)
 		}							\
 		rw_unlock(_w, _b);					\
 		bch_cannibalize_unlock(c, &(op)->cl);			\
+		if (_r == -ENOSPC) {					\
+			wait_event((c)->try_wait,			\
+				   !(c)->try_harder);			\
+			_r = -EINTR;					\
+		}							\
 	} while (_r == -EINTR);						\
 									\
 	_r;								\
@@ -375,8 +380,7 @@ void bch_btree_node_write(struct btree *, struct closure *);
 void bch_cannibalize_unlock(struct cache_set *, struct closure *);
 void bch_btree_set_root(struct btree *);
 struct btree *bch_btree_node_alloc(struct cache_set *, int, struct closure *);
-struct btree *bch_btree_node_get(struct cache_set *, struct bkey *,
-				int, struct btree_op *);
+struct btree *bch_btree_node_get(struct cache_set *, struct bkey *, int, bool);
 
 int bch_btree_insert_check_key(struct btree *, struct btree_op *,
 			       struct bkey *);

drivers/md/bcache/super.c

@@ -1436,12 +1436,14 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 
 	c->sort_crit_factor = int_sqrt(c->btree_pages);
 
-	mutex_init(&c->bucket_lock);
-	mutex_init(&c->sort_lock);
-	spin_lock_init(&c->sort_time_lock);
 	closure_init_unlocked(&c->sb_write);
+	mutex_init(&c->bucket_lock);
+	init_waitqueue_head(&c->try_wait);
 	closure_init_unlocked(&c->uuid_write);
+	spin_lock_init(&c->sort_time_lock);
+	mutex_init(&c->sort_lock);
 	spin_lock_init(&c->btree_read_time_lock);
+
 	bch_moving_init_cache_set(c);
 
 	INIT_LIST_HEAD(&c->list);
@@ -1529,7 +1531,7 @@ static void run_cache_set(struct cache_set *c)
 			goto err;
 
 		err = "error reading btree root";
-		c->root = bch_btree_node_get(c, k, j->btree_level, &op);
+		c->root = bch_btree_node_get(c, k, j->btree_level, true);
 		if (IS_ERR_OR_NULL(c->root))
 			goto err;